Osteosarcoma of the skull base presenting as a petrocavernous pseudoaneurysm and masquerading as an intracranial abscess: illustrative case.

BACKGROUND: Telangiectatic osteosarcoma (TOS) is a rare and aggressive high-grade malignant neoplasm composed of blood-filled or empty cystic spaces resembling aneurysmal bone cysts. Uncommonly, TOSs can occur in the skull base. OBSERVATIONS: The authors present a case of a TOS that presented as a petrocavernous carotid pseudoaneurysm and then masqueraded as an intracranial abscess. The prognosis for TOSs with intracranial involvement is typically unfavorable and inversely related to the degree of intracranial involvement. LESSONS: Skull-based malignancies should be part of the differential diagnosis for a rapidly progressing lesion. Recovery of polymicrobial organisms during endoscopic sinus surgery should prompt reconsideration of the differential diagnosis. Postinflammatory changes from endovascular coiling have been described and can confound imaging and clinical findings.

Cadaveric Study of an Endoscopic Keyhole Middle Fossa Craniotomy Approach to the Superior Semicircular Canal.

OBJECTIVE: Demonstrate that an endoscopic keyhole approach to the middle cranial fossa is technically feasible for repair of semicircular canal dehiscence. STUDY DESIGN: Cadaveric technical feasibility/methods development study. SETTING: Tertiary care military medical center. PATIENTS: Three fresh cadaveric heads (six sides). INTERVENTION(S): Endoscopic minimally invasive approach to the middle cranial fossa using the Medtronic Fusion Guidance system. MAIN OUTCOME MEASURE(S): Ability to identify the surgical landmarks of the middle cranial fossa and successfully identify and instrument the superior semicircular canal. RESULTS: In every attempt, the arcuate eminence was successfully identified under endoscopic visualization and with the assistance of surgical navigation. The superior semicircular canal was unroofed, and its location confirmed visually and with the navigation system. The opened canal was then plugged with bone wax, bone pate, and covered with fascia. The 15-mm burr hole craniotomy provided ample room for one working instrument and a 4-mm 0-degree endoscope. CONCLUSION: The endoscopic keyhole approach to superior semicircular canal dehiscence is technically feasible in a human cadaveric model. Further studies will determine 1) if this approach is possible and safe in vivo, 2) is associated with improved surgical outcomes, and 3) if surgical navigation aids in this approach.

Wartime decompressive craniectomy: technique and lessons learned.

OBJECT: Decompressive craniectomy (DC) with dural expansion is a life-saving neurosurgical procedure performed for recalcitrant intracranial hypertension due to trauma, stroke, and a multitude of other etiologies. Illustratively, we describe technique and lessons learned using DC for battlefield trauma. METHODS: Neurosurgical operative logs from service (October 2007 to September 2009) in Afghanistan that detail DC cases for trauma were analyzed. Illustrative examples of frontotemporoparietal and bifrontal DC that depict battlefield experience performing these procedures are presented with attention drawn to the L.G. Kempe hemispherectomy incision, brainstem decompression techniques, and dural onlay substitutes. RESULTS: Ninety craniotomies were performed for trauma over the time period analyzed. Of these, 28 (31%) were DCs. Of the 28 DCs, 24 (86%) were frontotemporoparietal DCs, 7 (25%) were bifrontal DCs, and 2 (7%) were suboccipital DCs. Decompressive craniectomies were performed for 19 penetrating head injuries (13 gunshot wounds and 6 explosions) and 9 severe closed head injuries (6 war-related explosions and 3 others). CONCLUSIONS: Thirty-one percent of craniotomies performed for trauma were DCs. Battlefield neurosurgeons use DC to allow for safe transfer of neurologically ill patients to tertiary military hospitals, which can be located 8-18 hours from a war zone. The authors recommend the L.G. Kempe incision for blood supply preservation, large craniectomies to prevent brain strangulation over bone edges, minimal brain debridement, adequate brainstem decompression, and dural onlay substitutes for dural closure.

Concomitant cranial and ocular combat injuries during Operation Iraqi Freedom.

BACKGROUND: Concomitant cranial and ocular injuries were frequently seen in combat casualties during Operation Iraqi Freedom. The incidence of these injuries is reported along with an interventional case series. METHODS: A retrospective review was conducted of all surgical patients treated by U.S. Army neurosurgeons and ophthalmologists in Iraq from December 2005 to April 2006. RESULTS: Out of 104 patients with cranial trauma and 158 patients with ocular trauma, 34 had both cranial and ocular injuries (32.7 and 21.5% of patients with cranial and ocular injuries, respectively). Neurosurgical procedures included exploratory craniotomy, decompressive craniectomy, and frontal sinus surgery. Ophthalmologic surgical procedures included globe exploration, open globe repair, primary enucleation, orbital fracture repair, lateral canthotomy and cantholysis, and repair of lid and periocular lacerations. Patients with cranial trauma had a higher incidence of orbital fracture, orbital compartment syndrome, and multiple ocular injuries compared with patients without cranial trauma (odds ratio 6.4, 3.9, and 3.3, respectively). CONCLUSION: A strong association exists between cranial and ocular trauma in combat casualties treated during Operation Iraqi Freedom. Combat health support personnel should maintain a high level of suspicion for one of these injuries when the other is present. Co-locating neurosurgeons and ophthalmologists in support of combat operations facilitates the optimal treatment of patients with these combined injuries.

A device for cooling localized regions of human cerebral cortex. Technical note.

Neurosurgeons use invasive mapping methods during surgery to understand the functional neuroanatomy of patients. Electrical stimulation methods are used routinely for the temporary disruption of focal regions of cerebral cortex so that the surgeon may infer the functional role of the brain site being stimulated. Although it is an efficient and useful method, modes of electrical stimulation mapping have significant limitations. Neuroscientists use focal cooling to effect a more controlled disruption of cortical functions in experimental animals, and in this report, the authors describe their experience using a device to achieve this same objective in patients undergoing neurosurgery. The cooling probe consists of a stainless steel chamber with thermocouples and electroencephalography (EEG) recording contacts. Active cooling is achieved by infusing chilled saline into the chamber when the cooling probe is positioned on the pial surface. Experiments were performed in 18 patients. Temperature gradient measurements indicate that the entire thickness of gray matter under the probe is cooled to temperatures that disrupt local synaptic activity. Statistically significant changes in spontaneous and stimulus-evoked EEG activity were consistently observed during cooling, providing clear evidence of reversible disruption of physiological functions. Preliminary findings during functional mapping of the Broca area demonstrated qualitative differences between the temporary neurological deficits induced by cooling and those caused by electrical stimulation. These findings indicate the safety and utility of the cooling probe as a neurosurgical research tool. Additional rigorously designed studies should be undertaken to correlate the effects of cooling, electrical stimulation, and focal lesioning.